Code Generation & the Runtime

Back end · registers · GC · JIT

1:00

How the compiler back end turns IR into machine code — instruction selection, register allocation, stack frames, and the four execution models including JIT and garbage collection.

By the end, you can

Sequence the five stages of the compiler back-end pipeline in order.
Explain how instruction selection tiles an IR tree with instruction patterns.
Describe what an interference graph is and how graph coloring assigns registers.
Explain why spilling occurs and what the allocator does when it runs out of registers.
State why SSA form makes register allocation solvable in linear time.
Describe what a stack frame contains and distinguish the prologue from the epilogue.
Contrast the four execution models (AOT, interpreter, bytecode VM, JIT) and give examples of each.
Explain the JIT warmup cost and when AOT outperforms JIT.
Trace the mark-and-sweep algorithm and explain why GC frees the unreachable rather than the unused.
Identify the key limitation of reference counting with respect to cycles.

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